Coil device and method of manufacturing coil device

Abstract

Provided is a coil device having a first coil and a second coil insulated by an insulating film, and deformation of the insulating film is suppressed. A coil device includes: a first insulating film provided in contact with a first direction side of a substrate; a spiral-shaped first coil part provided in contact with a first direction side of the first insulating film; a second insulating film provided to cover a first direction side of the first coil part and the first direction side of the first insulating film where the first coil part is not provided; a spiral-shaped second coil part provided in contact with a first direction side of the second insulating film; and a groove provided on a surface on the first direction side of the second insulating film in a region inside an outer peripheral edge of the second coil part in plan view.

What is claimed is: 
     
         1 . A coil device comprising:
 a substrate having a first main surface and a second main surface opposed to the first main surface;   a first insulating film provided in contact with a first direction side of the substrate, with the first direction being a direction from the second main surface to the first main surface;   a first coil part provided in contact with a first direction side of the first insulating film and being a spiral-shaped conductiv film in a plan view seen from a direction opposite to the first direction;   a second insulating film provided to cover a first direction side of the first coil part and the first direction side of the first insulating film where the first coil part is not provided;   a second coil part being a spiral-shaped conductive film in the plan view and provided in contact with a first direction side of the second insulating film; and   at least one first groove provided on the second insulating film in a region inside an outer peripheral edge of the second coil part in the plan view and having a width in the first direction on a surface on the first direction side of the second insulating film.   
     
     
         2 . The coil device according to  claim 1 , 
 wherein the at least one first groove is arranged between the adjacent conductive film of the second coil part in a cross-sectional view of the substrate.   
     
     
         3 . The coil device according to  claim 1 , 
 wherein the at least one first groove and the second coil part are provided in positions not overlapping with each other in the plan view.   
     
     
         4 . The coil device according to  claim 1 ,
 wherein the second insulating film has an outer shape of a rectangle composed of sides in a second direction parallel to the first main surface and sides in a third direction perpendiculat to the second direction in the plan view, and   wherein the at least one first groove has a straight part extending parallel to at least one of the second direction and the third direction.   
     
     
         5 . The coil device according to  claim 1 , 
 wherein each first groove of the at least one first groove has a part extending parallel to a part of the outer peripheral edge of the second insulating film closest to the first groove in the plan view.   
     
     
         6 . The coil device according to  claim 1 , 
 wherein the at least one first groove is spiral-shaped in the plan view.   
     
     
         7 . The coil device according to  claim 6 , 
 wherein a width in a direction perpendicular to the first direction of the at least one first groove in a cross-sectional view is equal to a width in a direction perpendicular to the first direction between the adjacent conductive film of the second coil part.   
     
     
         8 . The coil device according to  claim 1 , 
 wherein the second coil part is arranged to straddle a step between the surface on the first direction side of the second insulating film in a region where the at least one first groove is not provided and a bottom surface of the at least one first groove in the plan view.   
     
     
         9 . The coil device according to  claim 8 , 
 wherein each first groove of the at least one first groove has a part extending parallel to a part of the outer peripheral edge of the second insulating film closest to the first groove in the plan view.   
     
     
         10 . The coil device according to  claim 8 , 
 wherein a width in the first direction of the second coil part is equal to or larger than the width in the first direction of the at least one first groove.   
     
     
         11 . The coil device according to  claim 1 , 
 further comprising at least one second groove provided on the surface on the first direction side of the second insulating film and having a width in the first direction in a region outside the outer peripheral edge of the second coil part in the plan view.   
     
     
         12 . The coil device according to  claim 11 ,
 wherein the second insulating film has an outer shape of a rectangle composed of sides in a second direction parallel to the first main surface and sides in a third direction perpendiculat to the second direction in the plan view, and   wherein the at least one second groove has a straight part extending parallel to at least one of the second direction and the third direction.   
     
     
         13 . The coil device according to  claim 11 , 
 wherein each second groove of the at least one second groove has a part extending parallel to a part of the outer peripheral edge of the second insulating film closest to the second groove in the plan view.   
     
     
         14 . The coil device according to  claim 1 , 
 wherein the outer shape of the second insulating film extends along the outer peripheral edge of the second coil part in the plan view.   
     
     
         15 . The coil device according to  claim 1 , 
 wherein the width in the first direction of the at least one first groove is less than or equal to 50% of a width in the first direction of the second insulating film.   
     
     
         16 . The coil device according to  claim 1 , 
 wherein the second insulating film includes polyimide.   
     
     
         17 . A method of manufacturing a coil device comprising:
 forming a first insulating film in contact with a first direction side of a substrate having a first main surface and a second main surface opposed to the first main surface, with the first direction being a direction from the second main surface to the first main surface;   forming a first coil part being in contact with a first direction side of the first insulating film and being a spiral-shaped conductiv film in plan view seen from a direction opposite to the first direction after the forming of the first insulating film;   forming a second insulating film to cover a first direction side of the first coil part and to be in contact with the first direction side of the first insulating film where the first coil part is not provided after the forming of the first coil part and then forming an outer shape of the second insulating film;   forming a second coil part being in contact with a first direction side of the second insulating film and being a spiral-shaped conductive in the plan view after the forming of the outer shape of the second insulating film;   baking in which the second insulating film is heated and cured after the forming of the outer shape of the second insulating film or after the forming of the second coil part; and   forming at least one groove having a width in the first direction on a surface on the first direction side of the second insulating film by etching, in a region inside an outer peripheral edge of the second coil part in the plan view, after the forming of the outer shape of the second insulating film and before the baking.   
     
     
         18 . The method of manufacturing the coil device according to  claim 17 ,
 wherein the forming of the at least one groove is performed after the forming of the outer shape of the second insulating film, and   wherein the forming of the second coil part is performed after the forming of the at least one groove.   
     
     
         19 . The method of manufacturing the coil device according to  claim 17 ,
 wherein the forming of the second coil part is performed after the forming of the outer shape of the second insulating film, wherein in the forming of the second coil part, the second coil part is formed by forming a conductive film on the surface on the first direction side of the second insulating film, forming a resist with a shape of the second coil part on an upper surface of the conductive film, and removing the conductive film in a region not overlapping the resist in the plan view by etching,   wherein the forming of the at least one groove is performed after the forming of the second coil part, and   wherein in the forming of the at least one groove, the at least one groove is formed on the second insulating film in a region not overlapping the resist in the plan view by etching.   
     
     
         20 . The method of manufacturing the coil device according to  claim 17 ,
 wherein the forming of the second coil part is performed after the forming of the outer shape of the second insulating film,   wherein in the forming of the second coil part, the second coil part is formed by forming a conductive film on the surface on the first direction side of the second insulating film, forming a resist with a shape of the second coil part on an upper surface of the conductive film, removing the conductive film in a region not overlapping the resist in the plan view by etching, and removing the resist,   wherein the forming of the at least one groove is performed after the forming of the second coil part, and   wherein in the forming of the at least one groove, the at least one groove is formed on the second insulating film in a region not overlapping the second coil part in the plan view by etching.